Connective Tissue and Extracellular Matrix

Connective tissue is a group of tissue types, which significantly differ in form and function from each other, but share common features in development and structural organization. It is involved in the structure and support of an organism fills 

Connective tissues have often been reported in Raman and FT-IR images adjacent to epitheUum or carcinomas. Articular cartilage [15], ECM damage [16], and sarcoma, which is a neoplastic process originating within connective tissue [17], were studied by Raman spectroscopy. Applications of vibrational spectroscopic imaging to bone, which belongs to supportive connective tissue and is considered as hard tissue, are described in Chapter 4 of this book. 

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The stellate cells are also called perisinusoidal or Ito cells. There are approximately 5 to 20 of these cells per 100 hepatocytes. The stellate cells are lipid-filled cells (the primary storage site for vitamin A). They also control the turnover of hepatic connective tissue and extracellular matrix and regulate the contractihty of the sinusoids. When cirrhosis of the liver is present, the stellate cells are stimulated by various signals to increase their synthesis of extracellular matrix material. This, in turn, diffusely infiltrates the hver, eventually interfering with the function of the hepatocytes. 

Kielty, C.M., Hopkinson, 1., Grant, M.E. Collagen structure, assembly and organization in the extracellular matrix. In Connective Tissue and its Heritable Disorders Wiley-Liss, Chichester, pp. 103-147, 1993. 

Kielty, C. M., and Grant, M. E. (2002). The Collagen Family Structure Assembly and Organization in the Extracellular Matrix. In Connective Tissue and its Heritable Disorders, (P. M. Royce andB. Steinmann, Eds.), pp. 159-222. Wiley-Liss, New York. 

Scott, J. E., and Thomlinson, A. M. (1998). The structure of interfibrillar proteoglycan bridges ( shape modules ) in extracellular matrix of fibrous connective tissues and their stability in various chemical environments./. Anat. 192, 391-405. 

The mineralized matrix of bone tissue is strained when loaded. Macro-molecular mechanical connections between the extracellular matrix and the osteocytic cell membrane exist and these connections may be capable of transmitting information from the strained extracellular matrix to the bone cell nuclear membrane. The basis of this mechanism is the physical continuity of the transmembrane integrin molecule, which is connected extracellularly with the macromolecular collagen of the organic matrix and intracellularly with the... 

All of these structures have an epithelial lining that lies at the interface as well as extracellular matrix including basement membranes and loose connective tissue that supports the cellular layers (Table 3.2). These tissues are similar in their general structure they all have an inner cellular layer, supportive connective tissue, and an outer cellular layer. It is important to be familiar with the structure of these tissues to be able to analyze how external and internal mechanical forces are transduced at both the macroscopic and microscopic level into and out of cells. The effect of mechanical loading on these tissues is complex, but as discussed above, with increased frictional forces on the epidermis, the surface layer of skin actually increases the thickness of the epidermis. 

Connective Tissue Formation. Protein-lysine 6-oxidase (lysyl oxidase) is a cuproenzyme that is essential for stabilization of extracellular matrixes, specifically the enzymatic cross-linking of collagen and elastin. Complex mechanisms involve the deamination of lysine and hydrolysine residues at specific extracellular sites. The enzyme is highly associated with connective tissue and located in the aorta, dermal con-... 

Hyaluronan is continuously synthesized and secreted by fibroblasts, keratino-cytes, chondrocytes and other specialized cells in the extracellular matrix (ECMs) throughout the body. It is synthesized by HA synthase (see also Chapter 9) at the inner face of the plasma membrane [98]. The level of HA synthesis is very high in skin and cartilage [99]. Hyaluronic acid is not one of the major components of the ECMs of the connective tissues, but it is found in various locations such as synovial fluid, vitreous humor, and umbilical cords [100]. Its biological functions include the maintenance of mechanical properties such as swelling in connective tissues and control of tissue hydration, providing lubricating properties in synovial fluid and heart valves. 

Skeletal muscle fibers are connected to the extracellular matrix (ECM) that is composed of highly aligned cables of collagen with nanoscale-feature sizes. The ECM provides structural and functional support to muscle fibers. The connective tissue offers support and protection for the delicate cells and allows them to withstand the forces of contraction. It also provides pathways for the passage of blood vessels and nerves. 

Oxidation stress is unbalanced between prooxidants and natural antioxidants in body that lead to several diseases such as rheumatoid. Hyaluronic acid (HA), is a high molecular weight biopolysacharide, is found in the extracellular matrix of soft connective tissues and is particularly concentrated in synovial fluid (SF). Half-live time of Hyaluronan in SF is approximately 12 hrs in normal conditions. This process is accelerated under normal oxidation stress that generates troubles in human joints. 

The contribution of the extracellular matrix to spectra of breast tissue is shown in Figure 6. The spectra of low-grade breast tumours are vastly different from the spectra of cultured breast tumour cells. Breast tissue is composed predominantly of epithelial cells, connective tissue and adipose tissue. If we assume that cultured breast tumour cells and in situ breast tumour cells give rise to essentially similar spectra, then the differences seen between the spectra of tumours and cultured cells must reflect the presence of adipose and connective tissues. More specifically, a series of absorptions may be attributed to collagen and triglycerides. This example serves to illustrate not only the extent to which the extracellular matrix influences spectra, but also how spectroscopic studies of cultured cells can be used to identify such matrix effects. 

In biology, extracellular matrix (ECM) is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. ECM is the defining feature of connective tissue in animals. ECM includes the interstitial matrix and the basement membrane. 

Hyaluronic acid is a linear polysaccharide found in the highest concentrations in soft connective tissues where it fills an important structural role in the organization of the extracellular matrix (23,24). It has been used in ophthalmic preparations to enhance ocular absorption of timolol, a beta blocker used for the treatment of glaucoma (25), and in a viscoelastic tear formulation for conjunctivitis (26). The covalent binding of adriamycin and daunomycin to sodium hy-aluronate to produce water-soluble conjugates was recently reported (27). 

Bone is an extremely dense connective tissue that, in various shapes, constitutes the skeleton. Although it is one of the hardest structures in the body, bone maintains a degree of elasticity owing to its structure and composition. It possesses a hierarchical structure and, as most of the tissues, is nanostructured in fact, it is a nanoscaled composite of collagen (organic extracellular matrix) and hydroxycarbonate apatite, (HCA, bone mineral). This nanostructure is in intimate contact with the bone cells (several microns in size), which result (at the macroscopic level) in the bone tissue. Figure 12.2 shows the bone hierarchical ordering from the bone to the crystalline structure of HCA. 

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